1. Field of the Invention
The present invention relates to a vehicular power unit provided with an engine in which a crankshaft is rotatably supported by a crankcase and a transmission housed in the crankcase for shifting power transmitted from the crankshaft. A drive-side transmission sprocket wheel, onto which an endless transmission belt for transmitting power to a driving wheel is wound, is provided on an end of an output shaft of the transmission protruding from one side of the crankcase. In addition, a water pump is arranged on the same side of the crankcase in a position between the crankshaft and the output shaft. The vehicular power unit also includes a crankshaft to which a generator is attached, and a transmission having an output shaft for transferring power to a driving wheel is attached. An output retrieving member composing an output transfer mechanism is attached to the output shaft.
2. Description of Background Art
A conventional vehicular power unit including a water pump arranged between an output shaft of a transmission and a crankshaft arranged on one side of a crankcase is shown, for example, by JP Patent No. 3227972.
However, in the power unit disclosed in the JP Patent No. 3227972, a part of the water pump is arranged on a plane including a chain wound onto a drive sprocket provided to the output shaft of the transmission, the protruded amount of the water pump from one side of the crankcase is increased, and the power unit is prevented from being made compact.
Another, conventional power unit having a crankshaft to one end of which on one side a generator is attached, a transmission having an output shaft to one end of which on one side a drive sprocket is attached, and the crankshaft and the output shaft directed in the vehicle width direction are disposed in parallel with each other (See for example, JP-U No. 17699/1995).
In a power unit wherein a crankshaft and an output shaft are disposed in parallel with each other at an interval in an anteroposterior direction, when it is intended to shorten the distance between the crankshaft and the output shaft and downsize the power unit in the anteroposterior direction, a crankcase cover which covers a generator and a chain cover which covers a drive sprocket interfere with each other and hence the downsizing of the power unit is restricted in the anteroposterior direction. Further, a generator attached to a crankshaft functions as a rotary inertial mass to suppress the rotational fluctuation of the crankshaft and, when it is attempted to increase the diameter of the rotor of the generator in order to increase the rotary inertial mass without increasing the weight of the generator, a crankcase cover and a chain cover interfere with each other.